Benchmarking

Hi, i have 2 pieces of code that i created, both of which do exactly the same thing and i am trying to benchmark them to see which is generally more efficient. As such i used the code suggested by perldoc in the following format:

However both of my code samples are really short and as such come up with a result of "0 wallclock secs ( 0.00 usr + 0.00 sys = 0.00 CPU)"

The fact that both codes run fast is great and all, but both codes use completely different methods, and for the sake of future programming projects, i would like to know which code is functioning more efficiently than the other.

So what i am asking is, how do i benchmark code to fractions of a second?